Question

answer the following questions related to a reaction between hbr and nickel (ii) hydroxide
a. hbr is classified as a:
strong base
weak acid
weak base
strong acid
submit part
question 17
how many liters of hydrogen gas are produced at stp when 4.72 g of aluminum react with excess sulfuric acid according to the following chemical equation? (hint: use the molar volume of an ideal gas at stp: 22.4 l = 1 mol)
2 al(s) + 3 h₂so₄(aq) → al₂(so₄)₃(aq) + 3 h₂(g)
unit: h₂

Explanation:

Part 1 (Question about HBr classification)

HBr (Hydrobromic acid) is a strong acid because hydrohalic acids (except HF) are strong acids, meaning they dissociate completely in water. Strong bases are hydroxides of alkali/alkaline earth metals, weak acids partially dissociate, weak bases partially ionize. So HBr is a strong acid.

Step1: Calculate moles of Al

Molar mass of Al is 27.0 g/mol. Moles of Al = $\frac{mass}{molar\ mass}$ = $\frac{4.72\ g}{27.0\ g/mol}$ ≈ 0.1748 mol.

Step2: Use stoichiometry to find moles of H₂

From the equation, 2 mol Al produces 3 mol H₂. So moles of H₂ = 0.1748 mol Al × $\frac{3\ mol\ H₂}{2\ mol\ Al}$ ≈ 0.2622 mol.

Step3: Calculate volume of H₂ at STP

At STP, 1 mol gas = 22.4 L. Volume of H₂ = 0.2622 mol × 22.4 L/mol ≈ 5.87 L.

Answer:

D. Strong acid

Part 2 (Hydrogen gas volume calculation)